Nucleosides and glutamine are primary energy substrates for embryonic and adult chicken red cells

Abstract

It has been assumed that glucose is a major energy yielding substrate for chicken red blood cells. In this report we show that glucose fails to maintain cellular ATP levels in embryonic and mature chicken erythrocytes during overnight incubation. Of over a dozen metabolites tested, inosine, guanosine, and glutamine were the most efficacious ATP-sustaining substrates. Of seven potential citric acid cycle substrates, only glutamine significantly sustained ATP levels. Incubation with inosine plus glutamine sustained the ATP level at over 70% of the initial value found in embryonic chicken red cells. Uridine, cytidine, xanthosine, glutamate, and pyruvate were ineffective substrates. Similar results were obtained with adult erythrocytes, except that glutamine plus inosine fully sustained ATP levels during long-term incubation. Adenosine did not sustain ATP levels. Below 1 mM, the adenosine level was rapidly exhausted and above 1 mM its presence led to cell lysis. The ability of some nucleosides to maintain ATP levels is consistent with the high numbers of nitrobenzylthioinosine binding sites (nucleoside transporter sites) both in mature chicken red cells (approximately 10,000 sites/cell) and in embryonic red cells (approximately 30,000 sites/cell). Unlike pig red cells which switch from glucose to nucleosides at the erythrocyte stage, chicken cells show primary dependence on nucleoside metabolism at the embryonic stage.

Mouse Equilibrative Nucleoside Transporter 2 (mENT2) Transports Nucleosides and Purine Nucleobases Differing from Human and Rat ENT2

“…[2][3][4][5] Various structural analogues of nucleoside and nucleobase are cytotoxic and have found expanding therapeutic use as antineoplastic agents.6) Nucleosides and nucleobases are hydrophilic and require specific transporters for permeation through the cell membrane. [7][8][9] Several mammalian nucleoside transporters, which are expressed in the plasma membrane of cells, have been cloned.…”

“…[2][3][4][5] Various structural analogues of nucleoside and nucleobase are cytotoxic and have found expanding therapeutic use as antineoplastic agents.…”

Expression and loss of the transferrin receptor in growing and differentiating HD3 cells

“…ATP-assay The firefly fluorescence method of Stanley and Williams (1969) was used with the modification described by Mathew et al (1992).…”

“…With HD3 cells, the plasma membranes were prepared by lysis of the cells in water. With reticulocytes and erythrocytes, lysis buffer was used to disrupt the cells (Mathew et al, 1992). The membranes were recovered by centrifugation a t 7,700g for 20 min.…”

Influence of metal complexation on acidity of cytosine nucleosides: Part I, Li+, Na+ and K+ cation

“…Nucleosides are important precursors for nucleotide synthesis and also serve a variety of specialized functions [1][2][3][4][5]. Nucleoside analogues are cytotoxic and have found expanding therapeutic use as antineoplastic agents, such as cytarabin and gemcitabine, which possess the skeletal chemical structure of cytidine [1,6].…”